MalisisAdvert Mod 1.9, 1.8.9, 1.7.10 allow server owners to have an advertisment system inside Minecraft world. It comes with a single (non craftable) block that admins can use to display an advertisement panel. The true power of the mod comes from the possibility to display any image available from the internet.

First, an admin has to register and download images on the server. This is done with the command /malisisadvert which opens a GUI. There, he can add new adverts by specifying a name and an url. The server will download the image, and it will be available for the block.
The block, when placed in world and right clicked, allows admins to select what advert to display for it. Different models are also available for block and selectable from the GUI.